The ability to deliver high doses of radiation (up to 200 Gy and higher) to a tumor without significant damage to surrounding tissue would be a significant advancement in the radiation therapy of solid tumors. FeRx proposes to complete the preclinical and clinical development of targeted radioactive microparticles for the site-specific delivery of radionuclides to liver tumors. Magnetic Targeted Carriers (MTCs) are 0.5 to 5 micron particles composed of metallic iron and activated carbon. Results of SBIR phase I studies indicated that In111, Re188, and Y90 were efficiently and strongly bound to MTCs. Using a small externally positioned magnet, MTCs were effectively targeted to a swine liver where they were trapped. FeRx?s objectives are 1) to perform preclinical studies to support an Investigational Device Exemption submission and 2) to conduct a Phase I/Il safety and tolerability study in patients with liver cancer. In the first year, FeRx will complete the development of (90Y-DOTA)-MTCs, perform biodistribution studies in rabbits and swine, investigate the intra-tumoral biodistribution, and assess the radiotoxicity of high doses of localized radiation. In the second year, FeRx will submit an IDE and commence a phase I/II trial in patients with liver cancer to evaluate safety, tolerability, and preliminary efficacy.